A Tiered Approach to Integrating Genomic Tests Into Your Practice

Michael Scott Bowen, MPH


January 14, 2013

Editorial Collaboration

Medscape &

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Hello. I am Scott Bowen, Deputy Director of the Office of Public Health Genomics at the Centers for Disease Control and Prevention (CDC) in Atlanta. I am speaking to you as part of the CDC Expert Commentary Series on Medscape.

Advances in genomics and related fields are rapidly bringing a new era of medicine informed by new "personalization" tools in diagnosis, management, and prevention of many diseases of public health significance. However, although thousands of genomic tests are now available, many of them are not ready for "prime time." Like so many other areas of medicine, we know that the mere availability of a health application does not necessarily imply evidence of efficacy.

As a practicing physician you are faced with numerous choices every day in diagnosing, managing, and preventing disease, and it is increasingly difficult to dedicate time to research and stay abreast of changes in the field, particularly for emerging areas such as genomics. Meanwhile, patients are exposed to advertisements and online information about genomic tests and have new questions and demands. To help practitioners meet these challenges, the CDC Office of Public Health Genomics has recently created an evolving list of health-related genomic tests and family health history applications, stratified into 3 tiers according to the current availability of evidence-based recommendations supporting their use in practice. The list is intended to promote information exchange and dialogue among clinicians, researchers, policy makers, and the public.

Tier 1 applications are recommended for clinical use by evidence-based panels and are supported by a systematic review of evidence establishing the validity and utility of these tests for their intended use. Newborn screening is included in Tier 1, and other Tier 1 genomic applications could be used in practice to save lives. Examples include referring women to genetic counseling about BRCA1 and BRCA2 testing when they have specific high-risk family history patterns of breast or ovarian cancer, as recommended by the US Preventive Services Task Force. Another Tier 1 application is an evidence-based recommendation from the Evaluation of Genomic Applications in Practice and Prevention (EGAPP) Working Group. It involves screening all newly diagnosed persons with colorectal cancer for Lynch syndrome, and cascade testing for relatives of those identified as having Lynch syndrome, to inform and better target enhanced colorectal cancer surveillance and prevention efforts.

Tier 2 applications have evidence establishing validity and promising utility, but they lack evidence-based recommendations for their use, or evidence-based panels have simply found insufficient evidence. Information about these applications may be useful in discussions aimed at shared or informed decision-making between doctors and their patients. For example, pharmacogenomic testing can individualize the choice or dose of a drug on the basis of a patient's genotype. Mechanistic thinking may tell us that a particular test of this type should result in improved patient outcomes. However, most pharmacogenomic tests are considered Tier 2 applications. This is due either to lack of evidence supporting improved health outcomes or to the fact that the use of a particular test has not yet been evaluated by evidence-based panels.

Finally, Tier 3 applications have inadequate evidence of validity and/or utility, or recommendations against their use based on the overall balance of potential benefits and harms. Such applications are not ready for routine practice but may be considered in clinical and population research. Prominent examples of Tier 3 applications include the use of direct-to-consumer personal genetic tests for risk assessment and prevention of various common diseases and the use of whole genome sequencing/next-generation sequencing in clinical practice. The latter holds promise in the workup of patients with mysterious or undiagnosed conditions suspected to have a genetic nature. However, technical and interpretational issues must be resolved before such testing could be recommended for routine use in practice.

All tiers on the list are continually evolving, with recent additions reflecting cancer genomic tests and applications relevant to family health history. We encourage you to take a look at the list of applications by level of evidence on our Website, and come back often to check for updates. You might be surprised at how many tests are already classified as Tier 1 applications and have evidence-based recommendations for use in your clinic today or for referral of patients to other specialties.

Undoubtedly, the promise of genomic medicine will continue to grow in the next decade. In the meantime, this tier list describes how this information can be used to improve health, prevent disease, and save lives today. Thank you.

Web Resources

CDC. Public Health Genomics. Genetic Testing

CDC. Tier 1 Genomic and Family Health History Applications.

CDC. Tier 2 Genomic and Family Health History Applications.

CDC. Tier 3 Genomic and Family Health History Applications.

Michael Scott Bowen is the Deputy Director of CDC's Office of Public Health Genomics (OPHG). The Office was formed in 1997 to assess the impact of advances in human genetics and the Human Genome Projecton public health and disease prevention. OPHG serves as the focus for integrating genomics into public health research and programs for disease prevention and health promotion.Mr. Bowen oversees the development of national projects to establish public health research and program capacity in genomics, industry, and academic partnerships, and health agency program development. Much of Mr. Bowen's career has been focused on innovation to improve public health science and practice. Mr. Bowen joined CDC in 1992 and has also worked for the Agency for Toxic Substances and Disease Registry (ATSDR) where he served as a lead epidemiologist working on Superfund sites and as Deputy Chief of ATSDR's Health Investigations Branch. His past CDC roles include service as the Management Officer for the CDC Office of the Director and as the Deputy Director for CDC's Division of Public Health Surveillance and Informatics. Mr. Bowen earned a bachelor's degree in economics from Georgia State University and a master of public health degree in epidemiology from Tulane University's School of Public Health and Tropical Medicine.